Center beam railroad freight cars have been in use hauling lumber, plywood and other sheet materials for about twenty years. This type of car is disclosed in Taylor U.S. Pat. No. 3,244,120 and Wagner U.S. Pat. No. 3,734,031.
Baker U.S. Pat. No. 4,543,887 discloses an improved center beam car in which the principal distinguishing feature for lightweight and good strength is the use of a vertical center beam extending longitudinally the length of the car between bulkheads at each end of the car; the center beam comprising a center sill, a top sill parallel to and spaced above the center sill, and a plurality of vertical spaced apart columns rigidly connected at their lower ends to the center sill and at their upper ends to the top sill; and at each end of the car, a vertical plate extending from the center sill to the top sill, and from the bulkhead at that end inwardly along the center sill; the vertical plate being joined to the center sill, top sill, bulkhead and a plurality of said columns and having a width no more than about 20% and generally more than 10% of the distance between the bulkheads.
The vertical plates extending from the center sill to the top sill will generally have vertical inner edges and the area between those edges is to be maintained open, except for the columns, to keep the car lightweight. The area between the inner edges of the vertical plates at each end of the car is intended to be free of bracing. Also, the vertical plates desirably extend through the central portion of the columns to which they are joined.
It has been found that a railroad car according to the disclosure of the Baker U.S. Pat. No. 4,543,887 has a highly efficient load to empty weight ratio when the car length is in the range of about sixty to seventy-one feet long. However, longer cars, such as about seventy-two to ninety feet in length, which use the design of the Baker patent and are intended to carry maximum loads as dictated by axle capacities, have been found by studies to have insufficient strength to meet impact load requirements set by American railroads. A need accordingly exists for a further improved lightweight center beam railroad car which satisfies these requirements.